NTP Servers in France: Complete Guide & Comparison

Q: Does pool.ntp.org support IPv6?

Partially. Approximately 30% of servers in pool.ntp.org (and a similar share in fr.pool.ntp.org) publish an AAAA record in addition to A. RDEM Systems exposes its 12 stratum-2 NTS servers as dual-stack IPv4/IPv6; its GNSS stratum 1 is IPv4-only and serves no NTS. For a NIS 2 / ISO 27001 compliant architecture, plan at least one IPv6 source in addition to your IPv4 sources.

Q: Is there an NTS pool?

Yes. RDEM Systems operates ntp-pool.rdem-systems.com, one of the first public NTS pools available. It automatically distributes requests across 12 NTS servers in dual-stack IPv4/IPv6, with source authentication enabled by default. A single line of configuration is enough: server ntp-pool.rdem-systems.com iburst nts.

Q: How do I check if a French NTP server is still active?

The fast command-line method: ntpdate -q server.example.fr displays offset and stratum without modifying the local clock. Modern alternative: chronyd -Q 'server server.example.fr iburst minpoll 2 maxpoll 2'. For an in-browser diagnostic without installing an NTP client, use check-ntp.net: it queries the source from our AS206014 network and returns latency, stratum, NTS response and IPv6 support.

Q: What is the typical latency to a French NTP server from Paris?

For a French source well peered at a Paris IXP, expect 1 to 3 ms RTT. A German server (PTB Braunschweig): 10-20 ms. A Swedish server (Netnod): 25-40 ms. A US server (NIST): 80-150 ms. Low latency reduces RTD and improves offset precision.

Q: French Stratum 1 or Stratum 2: which should I choose?

A Stratum 1 server synchronizes directly to a primary reference (GNSS, atomic clock, PPS). A Stratum 2 synchronizes through one or more Stratum 1 servers. For 99% of use cases (application servers, workstations, monitoring), a well-chosen Stratum 2 offers more than sufficient precision (less than 1 ms). A local Stratum 1 is only justified by strict regulatory requirements (MiFID II, eIDAS, defense) or air-gapped environments.

By Richard DEMONGEOT · Servers verified 7 August 2026 · Published 10 April 2026 · 18 min read

Map of NTP servers in France: Stratum 1, Stratum 2 and Stratum 3+ by city — Public NTP servers in France — status as of 31 July 2026

The French servers we measured

This table is not a copied list: it is the result of our latest campaign, run from six distinct networks. Each column states what was obtained, never what is claimed — a server that advertises NTS without ever serving authenticated time comes out as “no”.

IPv4 and IPv6 are two separate columns, and they stay that way: a server reachable only over IPv4 and a server reachable over both families are not the same fact, and merging them would hide precisely what a page about coverage must show.

Time servers measured in France — campaign of 2026-08-07
Server	IPv4	IPv6	NTS	Stratum	State
`ntp.maison.bitschine.fr`	yes	yes	yes	S1	alive
`ntp.orlinum.fr`	yes	no	yes	S1	alive
`ntp-10.rdem-systems.com`	yes	yes	yes	S2	alive
`ntp-12.rdem-systems.com`	yes	yes	yes	S2	alive
`ntp-arn.tharyrok.eu`	yes	yes	yes	S2	alive
`ntp-teta.tharyrok.eu`	yes	yes	yes	S2	alive
`ntp.obspm.fr`	yes	—	yes	S2	alive
`ntp.picoweather.net`	yes	yes	yes	S2	alive
`ntp.viarouge.net`	yes	no	yes	S2	alive
`ntp1.rdem-systems.com`	yes	yes	yes	S2	alive
`ntp1.unistra.fr`	yes	yes	yes	S2	alive
`ntp11.rdem-systems.com`	yes	yes	yes	S2	alive
`ntp2.rdem-systems.com`	yes	yes	yes	S2	alive
`ntp2.unistra.fr`	yes	yes	yes	S2	alive
`ntp3.rdem-systems.com`	yes	yes	yes	S2	alive
`ntp4.rdem-systems.com`	yes	yes	yes	S2	alive
`ntp5.rdem-systems.com`	yes	yes	yes	S2	alive
`ntp6.rdem-systems.com`	yes	yes	yes	S2	alive
`ntp8.rdem-systems.com`	yes	yes	yes	S2	alive
`ntp9.rdem-systems.com`	yes	yes	yes	S2	alive
`paris.time.system76.com`	yes	yes	yes	S2	alive
`quatramaran.salle-s.org`	yes	yes	yes	S2	alive
`rapidooo.fr`	yes	no	yes	S2	alive
`vps-cqf1.orleans.ddnss.de`	—	yes	yes	S2	alive
`vps-par3.orleans.ddnss.de`	yes	yes	yes	S2	alive
`frcch1-ntp-001.aaplimg.com`	yes	yes	no	S1	alive
`ker.deuza.bzh`	yes	no	no	S1	alive
`ntp-0-hq.rdem-systems.com`	yes	no	no	S1	alive
`ntp-p1.obspm.fr`	yes	no	no	S1	alive
`ntp-scoob.duckdns.org`	yes	yes	no	S1	alive
`ntp.neel.ch`	yes	yes	no	S1	alive
`ntp.parat.fr`	yes	yes	no	S1	alive
`ntp.renater.fr`	yes	no	no	S1	alive
`ntp.teria.org`	yes	—	no	S1	alive
`ntp.vinua.net`	yes	no	no	S1	alive
`ntp1.sgjnet.net`	no	yes	no	S1	alive
`ntp3.143b.ch`	yes	yes	no	S1	alive
`time.kuro-home.net`	yes	—	no	S1	alive
`time1-v6.fwwhub.fr`	no	yes	no	S1	alive
`time2-v6.fwwhub.fr`	no	yes	no	S1	alive
`alibaba.le-loarer.org`	yes	no	no	S2	alive
`bethany.fangfufu.co.uk`	yes	yes	no	S2	alive
`chronos.ntp.k3s.fr`	no	yes	no	S2	alive
`clock-0.nubro.org`	yes	yes	no	S2	alive
`de.ntp.zattarasrl.it`	yes	yes	no	S2	alive
`fr01-prs.ntp.goon.ovh`	yes	yes	no	S2	alive
`gra-61.gombadi.com`	no	yes	no	S2	alive
`hueg.0b.yt`	yes	no	no	S2	alive
`lapier.re`	yes	yes	no	S2	alive
`mrs1.fr.ntp.li`	yes	no	no	S2	alive
`nixx.info`	yes	yes	no	S2	alive
`ns1.univ-montp3.fr`	yes	yes	no	S2	alive
`ntp-fr.inutile.pro`	yes	yes	no	S2	alive
`ntp-s2-ces.ntp.k3s.fr`	yes	yes	no	S2	alive
`ntp.accelance.net`	yes	no	no	S2	alive
`ntp.apio.systems`	yes	yes	no	S2	alive
`ntp.asrun.eu`	no	no	no	S2	alive
`ntp.cyberbits.eu`	yes	yes	no	S2	alive
`ntp.dahms.it`	no	—	no	S2	alive
`ntp.duckcorp.org`	yes	yes	no	S2	alive
`ntp.eigensystems.pl`	yes	yes	no	S2	alive
`ntp.eu.org`	yes	yes	no	S2	alive
`ntp.evolix.net`	yes	no	no	S2	alive
`ntp.functionnerd.de`	yes	yes	no	S2	alive
`ntp.gegeweb.org`	yes	yes	no	S2	alive
`ntp.home-dn.net`	yes	yes	no	S2	alive
`ntp.insa-lyon.fr`	yes	yes	no	S2	alive
`ntp.ipv6.evolix.eu`	no	yes	no	S2	alive
`ntp.lanel.fr`	yes	yes	no	S2	alive
`ntp.lasotel.net`	yes	no	no	S2	alive
`ntp.leffenet.fr`	no	no	no	S2	alive
`ntp.linuxpatch.com`	yes	yes	no	S2	alive
`ntp.lothaire.net`	yes	yes	no	S2	alive
`ntp.minoza.info`	yes	yes	no	S2	alive
`ntp.phys.univ-tours.fr`	yes	—	no	S2	alive
`ntp.polytechnique.fr`	yes	no	no	S2	alive
`ntp.relier.fr`	yes	no	no	S2	alive
`ntp.sceen.net`	yes	yes	no	S2	alive
`ntp.siberien.tf`	yes	no	no	S2	alive
`ntp.skhr.fr`	yes	no	no	S2	alive
`ntp.torrente.eu`	yes	yes	no	S2	alive
`ntp.tuxfamily.net`	yes	yes	no	S2	alive
`ntp.u-psud.fr`	yes	no	no	S2	alive
`ntp.unicaen.fr`	yes	—	no	S2	alive
`ntp.unice.fr`	yes	no	no	S2	alive
`ntp.univ-angers.fr`	yes	no	no	S2	alive
`ntp.uvsq.fr`	yes	—	no	S2	alive
`ntp.v6.goneco.de`	—	yes	no	S2	alive
`ntp.vetter-technologies.com`	no	yes	no	S2	alive
`ntp.vincennesvolleyclub.org`	yes	no	no	S2	alive
`ntp.wairunet.cloud`	yes	no	no	S2	alive
`ntp0.dioptre.fr`	yes	yes	no	S2	alive
`ntp0.octopuce.fr`	yes	yes	no	S2	alive
`ntp0.ovh.net`	yes	no	no	S2	alive
`ntp1.as212024.net`	yes	yes	no	S2	alive
`ntp1.ip6.mcasys.net`	no	yes	no	S2	alive
`ntp1.jussieu.fr`	yes	—	no	S2	alive
`ntp1.laas.fr`	yes	yes	no	S2	alive
`ntp1.moritz-fromm.de`	yes	yes	no	S2	alive
`ntp1.omdc.pl`	yes	yes	no	S2	alive
`ntp1.univ-rennes2.fr`	yes	no	no	S2	alive
`ntp16.ipv4.linocomm.net`	yes	no	no	S2	alive
`ntp16.ipv6.linocomm.net`	no	yes	no	S2	alive
`ntp18.ipv4.linocomm.net`	yes	no	no	S2	alive
`ntp18.ipv6.linocomm.net`	no	yes	no	S2	alive
`ntp2.apio.systems`	yes	yes	no	S2	alive
`ntp2.as212024.net`	yes	yes	no	S2	alive
`ntp2.emn.fr`	yes	—	no	S2	alive
`ntp2.ip6.mcasys.net`	no	yes	no	S2	alive
`ntp2.martinmoerch.dk`	yes	yes	no	S2	alive
`ntp2.novg.net`	yes	yes	no	S2	alive
`ntp2.omdc.pl`	yes	yes	no	S2	alive
`ntp2.univ-rennes2.fr`	yes	no	no	S2	alive
`ntp2.websters-computers.com`	yes	yes	no	S2	alive
`ntp21.ipv4.linocomm.net`	yes	no	no	S2	alive
`ntp21.ipv6.linocomm.net`	no	yes	no	S2	alive
`ntp22.ipv4.linocomm.net`	yes	no	no	S2	alive
`ntp23.ipv4.linocomm.net`	yes	no	no	S2	alive
`ntp24.ipv4.linocomm.net`	yes	no	no	S2	alive
`ntp3.ip6.mcasys.net`	no	yes	no	S2	alive
`ntp3.novg.net`	yes	yes	no	S2	alive
`ntp3.omdc.pl`	yes	yes	no	S2	alive
`ntp4.omdc.pl`	yes	yes	no	S2	alive
`ntp4.websters-computers.com`	yes	yes	no	S2	alive
`time-v6.fwwhub.fr`	no	yes	no	S2	alive
`time.eu.nerzhul.net`	yes	yes	no	S2	alive
`time.robmobz.co.uk`	yes	yes	no	S2	alive
`time.vandalsweb.com`	yes	—	no	S2	alive
`time.yas-online.net`	yes	yes	no	S2	alive
`vayu.oneyed.monster`	yes	no	no	S2	alive
`1.ext.ntp.senis.org`	yes	no	no	S3	alive
`2.ext.ntp.senis.org`	no	yes	no	S3	alive
`3.ext.ntp.senis.org`	no	no	no	S3	alive
`mail.ledow.org.uk`	yes	yes	no	S3	alive
`ntp.altinea.fr`	yes	yes	no	S3	alive
`ntp.arnouv.fr`	yes	no	no	S3	alive
`ntp.ciran28.fr`	yes	—	no	S3	alive
`ntp.crifo.org`	yes	yes	no	S3	alive
`ntp.haeiven.fr`	yes	yes	no	S3	alive
`ntp.komogoto.com`	yes	yes	no	S3	alive
`ntp.ksmoino.info`	yes	yes	no	S3	alive
`ntp.sophia.cnrs.fr`	yes	—	no	S3	alive
`ntp.univ-poitiers.fr`	yes	no	no	S3	alive
`ntp.valromey.com`	yes	—	no	S3	alive
`ntp01.dfuchshuber.de`	yes	yes	no	S3	alive
`ntp04.keragd.net`	no	no	no	S3	alive
`ntp2.ksmoino.info`	yes	yes	no	S3	alive
`ntp3.ksmoino.info`	yes	yes	no	S3	alive
`p5-vrs.dl.sm.ua`	yes	no	no	S4	alive
`canon.inria.fr`	no	no	no	—	dead
`chronos.cru.fr`	no	no	no	—	dead
`chronos.univ-brest.fr`	no	no	no	—	dead
`gra-nts1.itjntd.com`	no	no	no	—	silent
`lothaire.univ-lorraine.fr`	no	no	no	—	silent
`ntp-sop.inria.fr`	no	no	no	—	dead
`ntp.ardennesdecouverte.com`	no	no	no	—	silent
`ntp.cines.fr`	no	no	no	—	dead
`ntp.crashdump.fr`	no	no	no	—	dead
`ntp.demongeot.biz`	no	no	no	—	silent
`ntp.emi.u-bordeaux.fr`	yes	no	no	—	silent
`ntp.ensma.fr`	no	no	no	—	dead
`ntp.genoscope.cns.fr`	no	no	no	—	dead
`ntp.ilianum.com`	no	no	no	—	dead
`ntp.imag.fr`	no	—	no	—	silent
`ntp.midway.ovh`	—	—	no	—	dead
`ntp.sophia.mines-paristech.fr`	no	no	no	—	silent
`ntp1.onecert.fr`	no	—	no	—	dead
`ntp2.arcanite-infra.ch`	no	no	no	—	silent
`ntp2.imag.fr`	no	—	no	—	silent
`ntp_.hobbled.co.uk`	no	no	no	—	silent
`omdc.pl`	no	no	no	—	silent
`saturne.obs-besancon.fr`	yes	no	no	—	filtered
`syrte.obspm.fr`	no	no	no	—	silent
`time.freewebworld.fr`	no	no	no	—	silent
`time.resolvlab.com`	no	no	no	—	dead
`time1.freewebworld.fr`	no	no	no	—	silent
`time2.freewebworld.fr`	no	no	no	—	silent

177 named servers out of 334 machines measured in France. The other 157 are counted but not named: their operator has never published them, or their reverse name designates a subscriber line. They appear under a pseudonym in the dataset. A “no” under NTS does not mean the server is bad: it means no authenticated time was obtained from our six vantage points that day. A “—” means not measured. Why a server appears here at all: because it is published on the internet — its operator registered the address with pool.ntp.org, filled in a public registry record, or named it on their own pages. We say nothing about whether its use is permitted. This list carries no open-access or restricted-access claim, and being listed here is not an invitation to use a server: that decision belongs to its operator, and to them alone. Read their documentation before pointing a client at any of these names. The state column reports what our probes observed, never a policy: “filtered” means a server does not answer us while others cite it as their upstream — an observation, not permission. The state has four values, not two: alive (answered), filtered (does not answer us, but other servers publish it as their upstream: it serves time to a closed list), silent (quiet, but not yet long enough to conclude) and dead (silent across at least three campaigns AND more than four months). A dead server stays on display: removing it would have it rediscovered as a candidate in three months, and would make past counts impossible to recompute.

The complete data — all families, all countries, with reachability fractions across six vantage points — is in the downloadable dataset. We recommend no server: we measure, you filter.

Time server, NTP server, clock server: what's the difference?

None, in practice. All three name the same thing: a machine that hands out reference time over the network. Only the angle changes — time server and clock server name the function, NTP server names the protocol it speaks to deliver it. If you are looking for "a time server for my machines", an NTP server is what you want, and the addresses listed below answer the question.

Internet time server

A time server reachable from the public internet, as opposed to an internal one deployed inside your own network. Most workstations and servers today synchronise against an internet time server — typically the French NTP pool or their operating system's default. On a corporate estate, the right practice is still to run one or two internal servers which themselves sync outwards: it limits outbound traffic and guarantees that every machine shares the same clock, even during an outage.

Clock server

An older term, still common in Windows documentation and in industrial contexts. It sometimes covers historical protocols now abandoned (Time Protocol RFC 868, Daytime RFC 867). On any modern infrastructure, a "clock server" is an NTP server — or, when the required precision drops below the millisecond, a PTP server (IEEE 1588), used in finance and industry.

And where does stratum fit in?

Stratum measures the distance between a time server and its reference source: a server wired directly to an atomic clock or a GNSS receiver is stratum 1, one that syncs against it is stratum 2, and so on. It is a useful marker — but not the deciding criterion: it measures logical distance, not quality. We set out the full NTP stratum hierarchy in a dedicated guide.

NTP Pool France (fr.pool.ntp.org)

For the majority of use cases, the NTP pool France is the default choice. It is a geolocation-based DNS round-robin system that automatically redirects clients to nearby and reliable servers. 226 IPv4 servers and 202 IPv6 servers were participating in the France zone on 12 July 2026 (ntppool.org reading). The pool moves constantly: a dated figure is defensible, a floating one is not.

What the France zone carries, stratum by stratum

What ntppool.org declares, we probe. Here is the stratum breakdown of the machines our harvests of fr.pool.ntp.org actually reached — a count of the pool, not of the measured registry: the two answer two different questions.

Stratum	machines	share of answers	what it means
S1	28	10 %	own clock (GNSS, atomic, radio)
S2	194	69.3 %	follows a stratum 1
S3	53	18.9 %	follows a stratum 2
S4	5	1.8 %	four hops from the reference clock
Silent	7	—	did not answer our probe at harvest time

287 machines lent to the pool, 280 answered, 107 reachable over both IPv4 and IPv6. Machines are counted once even when we know both of their addresses. Harvest of 2026-08-05. A pool zone does not mean the country: the project tops up a sparse national zone with servers from neighbouring countries, so a zone says where the operator registered, not where the machine sits.

Address	Description
`fr.pool.ntp.org`	France zone, automatic assignment
`0.fr.pool.ntp.org` to `3.fr.pool.ntp.org`	Sub-zones (useful for configuring 4 distinct sources)

Advantages:

Decentralized, community-driven, natively supported by all operating systems
Reliable — the scoring system automatically removes failing servers
RDEM Systems is an active contributing member of the pool with >10 Stratum 2 servers

Limitations:

No NTS — the DNS round-robin mechanism is incompatible with NTS, because each server requires its own TLS certificate. You cannot authenticate a server whose address you do not know in advance.
No choice of specific server (the pool decides)
Variable quality depending on contributors

NTS in France — the current state

This page is a decision guide: which French source to use for which need, and how to configure it. It does not try to describe the world landscape. To place France among the other measured countries and see how much its NTS fleet rests on a single operator, go to the NTP and NTS map; for European detail, to the study of time servers in Europe.

What follows is the French picture, but it only makes sense next to our neighbours. We measured NTP and NTS servers across the whole of Europe, 2598 machines probed from 6 different networks: 21 countries serve NTS, 17 serve none — and in France, 17 operators serve it, two of them institutional: the University of Strasbourg, surfaced by the 31 July 2026 campaign, and the Paris Observatory / LNE-SYRTE, which holds the UTC(OP) realisation.

NTS (Network Time Security) cryptographically authenticates the time source and guarantees packet integrity, preventing server spoofing. The timestamps themselves are not encrypted: RFC 8915 treats them as non-confidential. It is the future of the protocol, but its deployment remains marginal: 192 machines serving NTS measured in Europe out of 2598 European machines (campaign of 7 August 2026, 6 networks), that is 7.4%.

In France, 29 machines serve NTS, held by 17 distinct operators. The table below names the ones we can name — part of the fleet belongs to operators our anonymity policy does not publish.

Server	Operator	Location	Stratum	Details
`ntp1` to `ntp12.rdem-systems.com`	RDEM Systems	Paris area (11/12)	2	NTS 12 servers, 7 of them on AS206014 (the rest on transit providers' and hosters' addressing), private NTS pool. `ntp7` is hosted in Frankfurt for geographic resilience — operator, contract and AS remain French, only the physical location is German.
`paris.time.system76.com`	System76 (USA)	Paris	2	NTS Dedicated Parisian node. NTS by default on Pop!_OS since 22.04
`ntp.viarouge.net`	Hubert Viarouge	Nancy	2	NTS VPS Debian, chrony 4.3, NTS on port 4460/TCP TLS 1.3. FR pool member
`ntp.obspm.fr`	Paris Observatory / LNE-OP	Paris	2	NTS Secondary server of the national time-frequency metrology laboratory, on Debian and chrony, synchronised to its own stratum 1 `ntp-p1.obspm.fr` (Meinberg M1000/MRS on a PPS tied to UTC(OP)). NTS has been open since 4 August 2026, documented by the operator itself, and measured by us the next day. Open access; the LNE-OP asks to be told about regular use.
`ntp1.unistra.fr`	University of Strasbourg	Strasbourg	—	NTS The first French institutional source we measured serving NTS (31 July 2026 campaign). Valid GÉANT CA certificate. Configure `ntp1`, not `ntp.unistra.fr`: the short name points at the same machine but its certificate does not cover it, and a conforming client refuses. Port 123 does not answer from our networks — hence no measured stratum.
`time.cloudflare.com`	Cloudflare	Anycast (Paris/Marseille nodes)	2	NTS US hyperscaler, not French but low latency from France

Observation: NTS remains a minority in France

Out of 334 measured French machines, 29 serve authenticated time, that is 8.7%. In our registry, RDEM Systems is the French operator with the most measured NTS machines (11 in France, out of the 12 NTS servers it operates).

Our NTS pool: `ntp-pool.rdem-systems.com`

Rather than declaring each server individually, point your client at our load-balanced pool entry ntp-pool.rdem-systems.com. It automatically distributes requests across all our NTS servers (ntp1 to ntp12.rdem-systems.com), with source authentication and packet-integrity protection enabled by default. NTS does not encrypt the timestamps — RFC 8915 treats them as non-confidential.

# /etc/chrony/chrony.conf - a single line is enough
server ntp-pool.rdem-systems.com iburst nts

Learn more about NTS (Network Time Security) →

European context: NTS reference operators

To put the French offering in perspective, here are the main NTS operators in Europe:

Operator	Country	NTS servers	Type
Netnod	Sweden	12+ (anycast + localized: Stockholm, Gothenburg, Malmo, Lulea, Sundsvall)	NTS pioneers, reference infrastructure
PTB	Germany	4	National metrology institute
SIDN Labs	Netherlands	Yes	.nl registry
Trifence AG	Switzerland	Yes (ntp.zeitgitter.net, ntp.trifence.ch)	Independent
RDEM Systems	France	12	Independent, NTP pool contributor

Do you run a time server in France? Declare it in our open repository: one YAML file, a single required field — the hostname. It enters the next campaign and gets measured from our six networks, NTS as well as NTP. This is not a list of recommended servers: it is what lets us find servers, where today we discover them through indirect routes — the upstream reference of other servers, the pool zones, operators' own pages — which systematically miss whoever never published anything. An e-mail to ntp@rdem-systems.com works just as well.

French Stratum 1 servers (primary sources)

NTP Stratum 1 server architecture: GNSS GPS/Galileo reception, Cesium reference and PPS signal

Reminder: Stratum 1 servers are intended to synchronize Stratum 2 servers, not end clients. Most require notifying the operator before use. Understand NTP stratum levels →

Server	Operator	Location	Reference	Access	Status
`ntp-p1.obspm.fr`	LNE-SYRTE, Observatoire de Paris	Paris	Cesium / H Maser, UTC(OP)	Open (notify first)	Active — national reference
`saturne.obs-besancon.fr`	LNE-LTFB, Obs. Besancon	Besancon	HP5071A atomic clock, traced to UTC(OP)	Stratum 2 only (notify first)	Active
`ntp.cines.fr`	CINES	Montpellier	Symmetricom NTS 200	Restricted to education/research	Active
`ntp1.jussieu.fr`	Universites Paris VI/VII	Paris	GPS Lantronix NTP-E1	Open (notify first)	Responds as S2 — historically listed as S1, but responds as Stratum 2 (April 2026)
`ntp.deuza.net`	Gandi/Parix	Paris	FreeBSD	Open	Active — stratum 1 on PPS in the campaign of 7 August 2026. The operator renamed the machine `ker.deuza.bzh`; both names point at the same address. Prefer the new name.
`ntp.genoscope.cns.fr`	Genoscope	Evry	Truetime NTS200	Stratum 2 (notify first)	Active (no guarantee, may be discontinued)
`time.kuro-home.net`	Independent	Besancon	GPS, LeonNTP	Open	Active

About the "REFUSED" status
A server responding with REFUSED is not necessarily out of service. It may indicate IP-based filtering, restricted access to the academic network (Renater), or a whitelist policy. The server is reachable but declines NTP requests from our test point.

French Stratum 2 servers

Network of NTP servers distributed across France — national time synchronization — Network of NTP servers distributed across France

Independent and community-operated

Server	Operator	Location	NTS	Notes
`ntp1` to `ntp12.rdem-systems.com`	RDEM Systems (AS206014)	Paris area (11/12)	NTS	12 servers, 11 of them in France, IPv4+IPv6, primarily Equinix, global NTP pool. The twelfth, `ntp7`, sits in Frankfurt. Since 2005
`ntp.accelance.net`	Accelance SA	Lyon	No	—

Academic and research network (Renater)

Server	Operator	Location	Notes
`ntp.obspm.fr`	Observatoire de Paris	Paris	Stratum 2 of LNE-OP — NTS active and reachable from our 6 networks in every campaign. NTS open since 4 August 2026. Open access; the LNE-OP asks to be told about regular use. For a stratum 1 source, see `ntp-p1.obspm.fr` — reserved for stratum 2 servers feeding significant sites.
`ntp1.unistra.fr`	University of Strasbourg	Strasbourg	The first French institutional source we measured serving NTS (31 July 2026 campaign; the Paris Observatory has served it since). Certificate issued by the GÉANT CA, valid. Note: the short name `ntp.unistra.fr` designates the same machine but fails certificate validation — configure `ntp1`. Port 123 does not answer us: usable over NTS, not over plain NTP from our vantage points.
`ntp.univ-rennes2.fr`	Univ. Rennes 2	Rennes	DNS round-robin (ntp1 + ntp2)
`ntp.lothaire.net`	Univ. Lorraine	Nancy	IPv4 + IPv6, alias (IP may change)
`ntp.laas.fr`	LAAS/CNRS	Toulouse	DNS alias
`ntp.u-psud.fr`	Univ. Paris-Sud	Orsay	Alias (IP may change)
`ntp.unicaen.fr`	Univ. Caen	Caen	Alias (IP may change)
`ntp.unice.fr`	Univ. Nice	Nice	CentOS
`ntp.ensma.fr`	ENSMA	Poitiers	no longer responds — silent from our 6 networks (0/6 in the campaign of 7 August 2026); it answered REFUSED on 31 July 2026
`ntp.polytechnique.fr`	Ecole Polytechnique	Saclay	Orolia/Safran hardware, redundant stratum 2. On request
`ntp.sophia.cnrs.fr`	DR20 CNRS	Sophia Antipolis	Responds as S3 — DNS alias (April 2026)
`ntp.univ-lyon1.fr`	CISM	Lyon	—
`ntp.univ-angers.fr`	Univ. Angers	Angers	—
`chronos.espci.fr`	ESPCI	Paris	silent — the name resolves, the machine answers none of our networks (NO_REPLY in the 12 and 31 July 2026 campaigns; out of scope since)
`ntp.univ-reims.fr`	Univ. Reims	Reims	Active (verified 31 July 2026)
`ntp.emi.u-bordeaux.fr`	Univ. Bordeaux	Bordeaux	Silent — resolves (CNAME to `clock.emi.u-bordeaux.fr`) but no longer answers (verified 31 July 2026)
`ntp2.emn.fr`	Ecole des Mines de Nantes	Nantes	Active (verified 31 July 2026)
`ntp.relier.fr`	Relier	France	Active (verified 31 July 2026)
`delphi.phys.univ-tours.fr`	Univ. Tours	Tours	Active (verified 31 July 2026)
`ntp.uvsq.fr`	Univ. Versailles	Versailles	Active — responds as Stratum 2 in the campaign of 7 August 2026 (Stratum 3 on 31 July 2026)

Hyperscalers (anycast with nodes in France)

Server	Operator	NTS	Specifics
`time.cloudflare.com`	Cloudflare	NTS	Anycast Paris/Marseille, very fast
`time.google.com`	Google	No	Leap smearing: spreads leap seconds over 24h instead of an instant step. Can cause offsets with other sources during leap second events
`time.facebook.com`	Meta	No	Stratum 1, very accurate. Leap smearing

These three services share one architectural choice: a single IP address announced from several sites at once, with BGP routing sending each client to the nearest node. That is what makes them fast — and also why you can neither tell which machine answered you nor name it in an audit, unlike the servers listed one by one earlier on this page. The mechanism, the real failover time and the capacity trap are covered in our BGP anycast guide.

French NTP appliance manufacturers

These companies do not offer public NTP services, but they are part of the French time ecosystem. They design and manufacture NTP/PTP appliances for enterprise, defense, and industrial use.

Bodet Time (Trementines, Maine-et-Loire) — since 1868. NETSILON range: GPS/GLONASS/Galileo/BeiDou, NTP/PTP, designed and manufactured in France. Multi-source (satellite, ALS162/DCF77 radio, network).
Gorgy Timing (Buzancais, Indre) — since 1979. LEDI range. Clients in defense, aerospace, industry, and transportation.

Summary and positioning

French NTP infrastructure has historically relied on the academic world: universities, CNRS, grandes ecoles, research institutes. These servers are stable — some have been running for over 20 years — but aging: often NTP v3, hardware sometimes 20+ years old, no NTS support, unmaintained reference lists.

Key findings:

The fr.pool.ntp.org pool (226 IPv4 servers (ntppool.org, 12 July 2026)) remains the pragmatic default choice
NTS remains a minority in France: 29 measured machines out of 334, that is 8.7%, held by 17 operators — among them RDEM Systems (11 machines measured in France out of the 12 NTS servers it operates), Observatoire de Paris / LNE-SYRTE, the University of Strasbourg, System76, Viarouge and OVH
Hyperscalers (Cloudflare, Google, Meta) offer massive but centralized, non-sovereign reliability
French NTP hardware is well represented (Bodet, Gorgy) but it is an appliance market, not a public service

Where does RDEM Systems fit?

RDEM Systems positions itself as the leading independent French NTS operator — a modern complement to the ecosystem, not a replacement. An active member of pool.ntp.org since 2005, with an infrastructure documented and proven over 20 years.

12 public NTS servers (ntp1 to ntp12.rdem-systems.com)
1 Stratum 1 GNSS server (GPS + Galileo) with PPS — technical details
Own network AS206014 for 7 of the 12 servers, peering at Parisian IXPs; the other 5 on transit providers' and hosters' addressing. Hosting mostly Equinix
Dual-stack IPv4/IPv6, 8 different TLDs, 24/7 monitoring
Reliability score available on ntppool.org

Recommended configuration

The examples below use Chrony; if you are still deciding which daemon to run, compare Chrony, ntpd and systemd-timesyncd before choosing.

Standard usage: Chrony + FR pool

# /etc/chrony/chrony.conf
# NTP Pool France (primary source)
pool fr.pool.ntp.org iburst maxsources 4

# Complementary servers (French operator, Stratum 2)
server ntp1.rdem-systems.com iburst
server ntp2.rdem-systems.com iburst

# Fast sync on startup
makestep 1 3
rtcsync

Secure usage: Chrony + NTS

# /etc/chrony/chrony.conf - with NTS
# FR pool as base (NTS not possible on the pool)
pool fr.pool.ntp.org iburst maxsources 3

# French NTS servers (source authentication + packet integrity)
server ntp1.rdem-systems.com iburst nts
server ntp2.rdem-systems.com iburst nts
server ntp3.rdem-systems.com iburst nts

makestep 1 3
rtcsync

High precision: Chrony + NTS + institutional Stratum 1

# /etc/chrony/chrony.conf - maximum precision
# Institutional Stratum 1 (notify operator before use)
server ntp-p1.obspm.fr iburst

# French NTS servers
server ntp1.rdem-systems.com iburst nts
server ntp2.rdem-systems.com iburst nts

# FR pool as complement
pool fr.pool.ntp.org iburst maxsources 2

makestep 1 3
rtcsync

Windows (w32tm)

REM French NTP servers (FR pool + RDEM Systems)
w32tm /config /manualpeerlist:"0.fr.pool.ntp.org 1.fr.pool.ntp.org ntp1.rdem-systems.com ntp2.rdem-systems.com" /syncfromflags:manual /reliable:no /update
net stop w32time && net start w32time
w32tm /resync

Frequently asked questions

Which public NTP servers should I use in France?

For most use cases, use the French NTP pool (fr.pool.ntp.org, 226 IPv4 servers (ntppool.org, 12 July 2026)). For secure synchronization with NTS, the options in France are RDEM Systems (11 NTS servers hosted in France out of the 12 it operates), paris.time.system76.com, ntp.viarouge.net, and ntp1.unistra.fr. Hyperscalers (time.cloudflare.com with NTS, time.google.com) are also reachable but not French-operated.

Which NTP servers support NTS in France?

17 operators serve NTS in France, for 29 measured machines as of 7 August 2026. Among those we can name: RDEM Systems (ntp1 to ntp12.rdem-systems.com, of which 11 measured in France), Observatoire de Paris / LNE-SYRTE, the University of Strasbourg (ntp1.unistra.fr), System76 with a Parisian node (paris.time.system76.com), Hubert Viarouge with a server in Nancy (ntp.viarouge.net) and OVH. The fr.pool.ntp.org pool does not support NTS due to the DNS round-robin mechanism.

Why is this count not 12? RDEM Systems operates 12 NTS servers, and three distinct things explain the gap with the 11 machines counted here. Geography first: ntp7 is hosted in Germany, and our registry counts machines by hosting country, not by operator nationality. Then service: a thirteenth server, ntp-0-hq, does sit in France but serves no NTS — it enters no NTS count. Finally measurement: a campaign counts what it queried, and the one of 7 August 2026 did not probe ntp2 — see the erratum. All three readings are accurate; they answer different questions.

Why use a French NTP server instead of time.google.com?

A French NTP server offers lower latency, does not depend on a foreign entity, and uses the standard NTP protocol. Google uses leap smearing (spreading leap seconds over 24 hours) which is incompatible with traditional NTP servers. Never mix sources with and without leap smearing.

Where can I find an up-to-date list of NTP servers in France?

The historical lists from Renater and CRU have not been updated since 2007-2015. This page maintained by RDEM Systems lists the active NTP servers in France: FR pool, NTS servers, institutional stratum 1, academic and independent stratum 2, and hyperscalers.

Does `pool.ntp.org` support IPv6?

Partially. Approximately 30% of servers in pool.ntp.org (and a similar share in fr.pool.ntp.org) publish an AAAA record in addition to A — the exact proportion varies with NTP Pool scoring and currently active servers. RDEM Systems exposes its 12 stratum-2 NTS servers as dual-stack IPv4/IPv6 — its GNSS stratum 1 is IPv4-only and serves no NTS. For a NIS 2 / ISO 27001 compliant architecture, plan at least one IPv6 source in addition to your IPv4 sources. Test IPv6 connectivity of your NTP source →

Is there an NTS pool?

Yes. RDEM Systems operates ntp-pool.rdem-systems.com, one of the first public NTS pools available. It automatically distributes requests across 12 NTS servers in dual-stack IPv4/IPv6, with source authentication enabled by default. A single line of configuration is enough: server ntp-pool.rdem-systems.com iburst nts. Learn more about NTS (Network Time Security) →

Is there a French NTS pool?

Yes — ntp-pool.rdem-systems.com is operated by a French entity (RDEM Systems SAS). Its core runs on AS206014, our own French autonomous system (7 servers, Equinix Paris datacenters), with peering at French IXPs (FranceIX, Equinix IXP Paris); the other five sit with third-party operators (IELO, IPSET, Arelion, OVH, Contabo). 11 of the 12 nodes are physically located in France; the twelfth, ntp-7, is in Frankfurt for geographic resilience — though on OVH's AS16276, a French autonomous system. Unlike US anycast solutions (Cloudflare, AWS), the operator falls under French law and every node is individually identifiable. Typical latency: 1 to 3 ms from French ISPs. See the full list of NTS servers in France or the dedicated NTS page.

How do I check if a French NTP server is still active?

The fast command-line method: ntpdate -q server.example.fr displays offset and stratum without modifying the local clock. Modern alternative: chronyd -Q 'server server.example.fr iburst minpoll 2 maxpoll 2'. For an in-browser diagnostic without installing an NTP client, use check-ntp.net: it queries the source from our AS206014 network and returns latency, stratum, NTS response and IPv6 support.

Can I contribute to the French NTP pool?

Yes, any operator with a stable public IP can join ntppool.org. Prerequisites: fixed IP (no NAT), synchronization within 100 ms of a reliable source, accepting ~10 req/s on average. RDEM Systems has contributed to the FR pool since 2005 with 12 servers. See why contribute to the NTP pool and our guide run an NTP pool server.

What is the typical latency to a French NTP server from Paris?

For a French source well peered at a Paris IXP, expect 1 to 3 ms RTT. A German server (PTB Braunschweig): 10–20 ms. A Swedish server (Netnod): 25–40 ms. A US server (NIST): 80–150 ms. Low latency reduces RTD and improves offset precision. Detailed measurements at the European NTP latency benchmark.

French Stratum 1 or Stratum 2: which should I choose?

A Stratum 1 server synchronizes directly to a primary reference (GNSS, atomic clock, PPS). A Stratum 2 synchronizes through one or more Stratum 1 servers. For 99% of use cases (application servers, workstations, monitoring), a well-chosen Stratum 2 offers more than sufficient precision (< 1 ms). A local Stratum 1 is only justified by strict regulatory requirements (MiFID II, eIDAS, defense) or air-gapped environments. Understand NTP stratum levels →

Free NTP Tools

Three independent tools to diagnose your time synchronization:

NTP Servers in France: Complete Guide & Comparison

The French servers we measured

Time server, NTP server, clock server: what's the difference?

Internet time server

Clock server

And where does stratum fit in?

NTP Pool France (fr.pool.ntp.org)

What the France zone carries, stratum by stratum

NTS in France — the current state

Observation: NTS remains a minority in France

Our NTS pool: ntp-pool.rdem-systems.com

European context: NTS reference operators

French Stratum 1 servers (primary sources)

French Stratum 2 servers

Independent and community-operated

Academic and research network (Renater)

Hyperscalers (anycast with nodes in France)

French NTP appliance manufacturers

Summary and positioning

Where does RDEM Systems fit?

Recommended configuration

Standard usage: Chrony + FR pool

Secure usage: Chrony + NTS

High precision: Chrony + NTS + institutional Stratum 1

Windows (w32tm)

Frequently asked questions

Which public NTP servers should I use in France?

Which NTP servers support NTS in France?

Why use a French NTP server instead of time.google.com?

Where can I find an up-to-date list of NTP servers in France?

Does pool.ntp.org support IPv6?

Is there an NTS pool?

Is there a French NTS pool?

How do I check if a French NTP server is still active?

Can I contribute to the French NTP pool?

What is the typical latency to a French NTP server from Paris?

French Stratum 1 or Stratum 2: which should I choose?

Free NTP Tools

Our NTS pool: `ntp-pool.rdem-systems.com`

Does `pool.ntp.org` support IPv6?